Agent Skills: FFmpeg Noise Reduction (2025)

CRITICAL GUIDELINES

Windows File Path Requirements

MANDATORY: Always Use Backslashes on Windows for File Paths

When using Edit or Write tools on Windows, you MUST use backslashes (\) in file paths, NOT forward slashes (/).

Quick Reference

| Task | Filter | Command Pattern | |------|--------|-----------------| | Video denoising (best) | nlmeans | -vf nlmeans=s=3:p=7:r=15 | | Video denoising (fast) | hqdn3d | -vf hqdn3d=4:3:6:4.5 | | GPU video denoising | nlmeans_vulkan | -vf nlmeans_vulkan | | Audio denoising | afftdn | -af afftdn=nf=-25 | | Adaptive temporal | atadenoise | -vf atadenoise |

When to Use This Skill

Use for noise reduction workflows:

• Cleaning low-light or high-ISO footage
• Removing film grain
• Reducing compression artifacts
• Cleaning audio recordings
• Broadcast signal cleanup
• Pre-processing before encoding

FFmpeg Noise Reduction (2025)

Comprehensive guide to video and audio denoising filters.

Video Denoising

nlmeans - Non-Local Means (Best Quality)

The highest quality software denoiser, using non-local means algorithm.

# Basic denoising
ffmpeg -i noisy.mp4 -vf "nlmeans" output.mp4

# Medium denoising (good default)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=3.0:p=7:r=15" output.mp4

# Strong denoising (very noisy footage)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=5.0:p=7:r=15" output.mp4

# Light denoising (preserve detail)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=1.5:p=5:r=9" output.mp4

# Denoise only chroma (preserve luma detail)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=3.0:sc=5.0:p=7:r=15" output.mp4

Parameters: | Parameter | Description | Default | Range | |-----------|-------------|---------|-------| | s | Denoising strength (sigma) | 1.0 | 0-30 | | p | Patch size | 7 | 1-99 (odd) | | pc | Patch size for chroma | 0 (same as p) | 1-99 | | r | Research window size | 15 | 1-99 (odd) | | rc | Research window for chroma | 0 (same as r) | 1-99 |

Strength guidelines: | s value | Use case | |---------|----------| | 1.0-2.0 | Light noise, preserve detail | | 2.0-4.0 | Moderate noise (typical) | | 4.0-6.0 | Heavy noise, low light | | 6.0+ | Extreme noise (quality loss) |

nlmeans_opencl - GPU-Accelerated NLMeans

OpenCL accelerated version, much faster.

# OpenCL denoising
ffmpeg -i noisy.mp4 \
  -vf "hwupload,nlmeans_opencl=s=3:p=7:r=15,hwdownload,format=yuv420p" \
  output.mp4

# Strong denoising with OpenCL
ffmpeg -i noisy.mp4 \
  -vf "hwupload,nlmeans_opencl=s=5:p=7:r=21,hwdownload,format=yuv420p" \
  output.mp4

nlmeans_vulkan - Vulkan-Accelerated NLMeans (FFmpeg 8.0+)

Cross-platform GPU acceleration using Vulkan.

# Vulkan denoising
ffmpeg -init_hw_device vulkan \
  -i noisy.mp4 \
  -vf "hwupload,nlmeans_vulkan=s=3:p=7:r=15,hwdownload,format=yuv420p" \
  output.mp4

# Full Vulkan pipeline
ffmpeg -init_hw_device vulkan=vk \
  -filter_hw_device vk \
  -hwaccel vulkan -hwaccel_output_format vulkan \
  -i noisy.mp4 \
  -vf "nlmeans_vulkan=s=3" \
  -c:v h264_vulkan output.mp4

hqdn3d - High Quality 3D Denoiser (Fast)

Faster than nlmeans with good results for moderate noise.

# Default settings
ffmpeg -i noisy.mp4 -vf "hqdn3d" output.mp4

# Custom settings (luma_spatial:chroma_spatial:luma_tmp:chroma_tmp)
ffmpeg -i noisy.mp4 -vf "hqdn3d=4:3:6:4.5" output.mp4

# Strong spatial denoising
ffmpeg -i noisy.mp4 -vf "hqdn3d=8:6:6:4" output.mp4

# Strong temporal denoising (for static scenes)
ffmpeg -i noisy.mp4 -vf "hqdn3d=4:3:12:9" output.mp4

# Light denoising
ffmpeg -i noisy.mp4 -vf "hqdn3d=2:1.5:3:2" output.mp4

Parameters: | Parameter | Description | Default | Range | |-----------|-------------|---------|-------| | luma_spatial | Luma spatial strength | 4.0 | 0-255 | | chroma_spatial | Chroma spatial strength | 3.0 | 0-255 | | luma_tmp | Luma temporal strength | 6.0 | 0-255 | | chroma_tmp | Chroma temporal strength | 4.5 | 0-255 |

atadenoise - Adaptive Temporal Averaging

Temporal denoiser that preserves motion.

# Basic temporal denoising
ffmpeg -i noisy.mp4 -vf "atadenoise" output.mp4

# Stronger denoising
ffmpeg -i noisy.mp4 -vf "atadenoise=0a=0.1:0b=0.2:1a=0.1:1b=0.2:2a=0.1:2b=0.2" output.mp4

# Adjust threshold and planes
ffmpeg -i noisy.mp4 -vf "atadenoise=s=9:p=5" output.mp4

Parameters: | Parameter | Description | Default | |-----------|-------------|---------| | 0a, 1a, 2a | Threshold A for planes 0,1,2 | 0.02 | | 0b, 1b, 2b | Threshold B for planes 0,1,2 | 0.04 | | s | Number of frames to average | 9 | | p | Planes to process | 7 (all) |

vaguedenoiser - Wavelet Denoiser

Uses wavelet transform for denoising.

# Basic wavelet denoising
ffmpeg -i noisy.mp4 -vf "vaguedenoiser" output.mp4

# Adjust threshold
ffmpeg -i noisy.mp4 -vf "vaguedenoiser=threshold=3:method=soft" output.mp4

# Stronger denoising
ffmpeg -i noisy.mp4 -vf "vaguedenoiser=threshold=6:nsteps=6" output.mp4

Parameters: | Parameter | Description | Default | Values | |-----------|-------------|---------|--------| | threshold | Denoising threshold | 2 | 0-inf | | method | Thresholding method | hard | hard, soft, garrote | | nsteps | Decomposition steps | 6 | 1-32 | | percent | Percent of full denoising | 85 | 0-100 |

fftdnoiz - FFT-Based Denoising

Frequency domain denoising.

# Basic FFT denoising
ffmpeg -i noisy.mp4 -vf "fftdnoiz" output.mp4

# Adjust sigma
ffmpeg -i noisy.mp4 -vf "fftdnoiz=sigma=8" output.mp4

# Strong denoising
ffmpeg -i noisy.mp4 -vf "fftdnoiz=sigma=15:block=32:overlap=0.8" output.mp4

owdenoise - Overcomplete Wavelet Denoiser

Another wavelet-based option.

# Basic wavelet denoising
ffmpeg -i noisy.mp4 -vf "owdenoise" output.mp4

# Adjust depth and strength
ffmpeg -i noisy.mp4 -vf "owdenoise=depth=10:ls=3:cs=3" output.mp4

removegrain - RemoveGrain

Classic grain/noise removal (from AviSynth).

# Mode 1 (basic)
ffmpeg -i noisy.mp4 -vf "removegrain=m0=1" output.mp4

# Different modes for different noise types
ffmpeg -i noisy.mp4 -vf "removegrain=m0=17:m1=17:m2=17" output.mp4

Audio Denoising

afftdn - FFT Denoiser (Recommended)

Powerful audio noise reduction using FFT.

# Basic audio denoising
ffmpeg -i noisy_audio.mp4 -af "afftdn" output.mp4

# Specify noise floor
ffmpeg -i noisy_audio.mp4 -af "afftdn=nf=-25" output.mp4

# Stronger noise reduction
ffmpeg -i noisy_audio.mp4 -af "afftdn=nf=-20:nt=w" output.mp4

# With noise profile (sample noise-only section first)
ffmpeg -i noisy_audio.mp4 -af "afftdn=nr=10:nf=-30:nt=w:om=o" output.mp4

# Adaptive noise floor
ffmpeg -i noisy_audio.mp4 -af "afftdn=nt=c:om=o:bn=9" output.mp4

Parameters: | Parameter | Description | Default | Range | |-----------|-------------|---------|-------| | nr | Noise reduction (dB) | 12 | 0.01-97 | | nf | Noise floor (dB) | -50 | -80 to -20 | | nt | Noise type | w | w=white, v=vinyl, s=shellac, c=custom | | bn | Number of noise bands | 15 | 3-33 | | rf | Residual floor (dB) | -38 | -80 to -20 | | om | Output mode | o | i=input, o=output, n=noise |

anlmdn - Non-Local Means Audio Denoiser

Audio equivalent of video nlmeans.

# Basic NLM audio denoising
ffmpeg -i noisy_audio.mp4 -af "anlmdn" output.mp4

# Adjust strength
ffmpeg -i noisy_audio.mp4 -af "anlmdn=s=0.0001" output.mp4

# Stronger denoising
ffmpeg -i noisy_audio.mp4 -af "anlmdn=s=0.001:p=0.01" output.mp4

Parameters: | Parameter | Description | Default | |-----------|-------------|---------| | s | Denoising strength | 0.00001 | | p | Patch radius | 0.002 | | r | Research radius | 0.006 | | m | Output mode | o (output) |

adeclick - Remove Clicks/Pops

Removes impulsive noise from audio.

# Remove clicks
ffmpeg -i clicked_audio.mp4 -af "adeclick" output.mp4

# Adjust parameters
ffmpeg -i clicked_audio.mp4 -af "adeclick=w=55:o=75" output.mp4

adeclip - Remove Clipping

Repairs clipped audio.

# Fix clipping
ffmpeg -i clipped_audio.mp4 -af "adeclip" output.mp4

Combined Workflows

Low-Light Video Enhancement

# Denoise + brighten + contrast
ffmpeg -i dark_noisy.mp4 \
  -vf "nlmeans=s=4:p=7:r=15,eq=brightness=0.1:contrast=1.2:saturation=1.1" \
  -c:v libx264 -crf 18 \
  enhanced.mp4

Interview Cleanup (Video + Audio)

# Clean both video and audio noise
ffmpeg -i interview.mp4 \
  -vf "hqdn3d=3:2:4:3" \
  -af "afftdn=nf=-30:nr=10,loudnorm" \
  -c:v libx264 -crf 20 \
  -c:a aac -b:a 192k \
  interview_clean.mp4

Film Grain Removal

# Strong nlmeans for film grain
ffmpeg -i grainy_film.mp4 \
  -vf "nlmeans=s=5:p=7:r=21" \
  -c:v libx264 -crf 18 -preset slow \
  degrained.mp4

# Preserve some grain (artistic choice)
ffmpeg -i grainy_film.mp4 \
  -vf "nlmeans=s=2.5:p=5:r=11" \
  -c:v libx264 -crf 18 \
  light_degrain.mp4

Compression Artifact Removal

# Remove blocking artifacts from highly compressed video
ffmpeg -i compressed.mp4 \
  -vf "hqdn3d=2:1.5:3:2,unsharp=5:5:0.3:5:5:0" \
  -c:v libx264 -crf 18 \
  cleaner.mp4

GPU-Accelerated Batch Processing

#!/bin/bash
# Process multiple noisy videos with GPU

for video in noisy_*.mp4; do
  output="clean_${video}"
  ffmpeg -init_hw_device vulkan \
    -i "$video" \
    -vf "hwupload,nlmeans_vulkan=s=3,hwdownload,format=yuv420p" \
    -c:v libx264 -crf 18 \
    "$output"
done

Filter Comparison

Video Denoising Speed vs Quality

| Filter | Quality | Speed | GPU Option | Best For | |--------|---------|-------|------------|----------| | nlmeans | Excellent | Slow | Yes (OpenCL/Vulkan) | Final output | | hqdn3d | Good | Fast | No | Real-time, previews | | atadenoise | Good | Medium | No | Static scenes | | vaguedenoiser | Good | Medium | No | Mixed content | | fftdnoiz | Good | Medium | No | Periodic noise |

Audio Denoising Comparison

| Filter | Quality | Speed | Best For | |--------|---------|-------|----------| | afftdn | Excellent | Fast | All-purpose | | anlmdn | Good | Medium | Speech | | adeclick | Specialized | Fast | Clicks/pops |

Parameter Tuning Tips

Video Denoising

1. Start conservative - Begin with s=2-3, increase if needed
2. Preserve edges - Lower patch size (p=5) preserves more detail
3. Test on samples - Process 10-second clips first
4. Consider GPU - nlmeans_opencl/vulkan are 5-10x faster
5. Match content - Static scenes tolerate stronger temporal denoising

Audio Denoising

1. Find noise floor - Listen to quiet sections
2. Use appropriate type - White noise vs vinyl vs custom
3. Don't over-process - Artifacts can be worse than noise
4. Check residual - Use om=n to hear what's being removed

Best Practices

1. Denoise before encoding - Noise compresses poorly
2. Preserve some texture - Over-denoising looks artificial
3. Match source quality - Don't denoise clean footage
4. Use GPU when available - Massive speed improvement
5. Combine filters carefully - Multiple denoisers can cause artifacts
6. Test different filters - Content-dependent results

This guide covers noise reduction for 2025. For video analysis and detection, see ffmpeg-video-analysis. For hardware acceleration, see ffmpeg-hardware-acceleration.